1. Field of the Invention
The present invention relates to a power transmitting coil used to wirelessly transmit a power and a wireless power transmitting apparatus wirelessly transmitting a power using the power transmitting coil.
2. Description of the Related Art
Generally, various portable terminals such as a cellular phone, a personal digital assistant (PDA), or the like, includes a power receiving apparatus such as a battery pack charged with a power, to supply the charged power to the portable terminal for operation of the portable terminal. The power receiving apparatus may receive a power supplied from an external charging apparatus.
The power receiving apparatus may include a battery cell module charged with the power, and a circuit for charging the power supplied from the external charging apparatus into the battery cell module and for discharging the power charged in the battery cell module into the portable terminal, among other components.
One known method of electrically connecting the charging apparatus to the power receiving apparatus is a connection between a terminal through which the power exits the charging apparatus and a terminal through which the power enters the power receiving apparatus, with or without an intermediary cable.
However, using this method, the terminal of the charging apparatus and the terminal of the power receiving apparatus may have different potential differences. Therefore, when the two terminals are connected to each other or disconnected from each other, an instantaneous discharging phenomenon can occur.
This instantaneous discharge phenomenon causes abrasion of the terminals. In addition, if foreign materials have accumulated in either terminal, said foreign materials may be exposed to heat from the instantaneous discharge phenomenon, such that there is a risk of an accident such as a fire or the like.
In addition, the power charged in the battery cell module of the power receiving apparatus naturally discharges into the environment through the terminal of the power receiving apparatus due to moisture or the like, such that a lifespan of the power receiving apparatus may decrease and performance of the power receiving apparatus may deteriorate.
Recently, a wireless power transmitting apparatus, which wirelessly transmits the power to the power receiving apparatus, has been suggested in order to solve the above-described problems of the terminal connection scheme.
The wireless power transmitting apparatus wirelessly transmits the power using, in one known method, electromagnetic induction. The power receiving apparatus receives the transmitted power and charges the received power in the battery cell module.
A number of efforts have been made to improve this system and method such that the power may be wirelessly transmitted stably and at high efficiency, such that the power receiving apparatus may receive the maximum amount of transmitted power.
In one known system, the wireless power transmitting apparatus includes a core assembly. The core assembly of the wireless power transmitting apparatus includes a core, and a power transmitting coil seated on the core.
In addition, the power receiving apparatus also includes a core assembly, and the core assembly of the power receiving apparatus includes a core and a power receiving coil seated on the core and receiving the power transmitted by the wireless power transmitting apparatus.
The power transmitting coil, included in the core assembly of the wireless power transmitting apparatus, and the power receiving coil, included in the core assembly of the power receiving apparatus, have different sizes due to characteristics thereof.
Specifically, since the power receiving coil of the power receiving apparatus should be connected to the portable terminal and provide a charging function, a size of the power receiving coil is determined according to a size of the power receiving apparatus.
In contrast, the power transmitting coil of the wireless power transmitting apparatus should be able to be mounted by the entire portable terminal in which the power receiving apparatus is located. Therefore, a size of the power transmitting coil of the wireless power transmitting apparatus should be larger than a size of the portable terminal.
Further, since the portable terminal generally has a rectangular shape, the power transmitting coil and the core included in the core assembly of the wireless power transmitting apparatus generally have oval or rectangular shapes rther than circular shapes.
However, since the power receiving apparatus of the portable terminal generally has a square shape, the power receiving coil included in the core assembly of the power receiving apparatus generally has a circular shape, and the core on which the power receiving coil is mounted also generally has a rectangular or circular shape.
The difference in the shapes and sizes of the two core assemblies, of the wireless power transmitting apparatus and the power receiving apparatus respectively, can create variance in the power received by the power receiving apparatus. That is, when the power receiving apparatus is placed on the wireless power transmitting apparatus, a power induced in the power receiving coil of the core assembly of the power receiving apparatus will vary according to a specific position at which the core assembly of the power receiving apparatus is placed relative to the core assembly of the wireless power transmitting apparatus.
The variance of the power induced in the power receiving coil also has a negative effect on communication of digital data transmitted between the wireless power transmitting apparatus and the power receiving apparatus. Therefore, a system which avoids such variance is desirable.